docs: def get_substituted_contents(contents, substitutions):
      """
      Perform a list of substitutions and return the result.
  
      contents: the starting string on which to beging substitutions
      substitutions: list of Substitution objects to call, in order, with the
          result of the previous substitution.
      """
      result = contents
      for sub in substitutions:
          result = sub.apply_and_get_result(result)
      return result